This invention relates to pistons for internal combustion engines, compressors, pumps, or the like. More specifically, it relates to an improved oil damped piston.
Prior art of possible relevance includes the following U.S. Pat. No. 2,817,562 issued to Fleming et al on Dec. 24, 1957; U.S. Pat. No. 3,528,667 issued to Spaven on Sept. 15, 1970; and U.S. Pat. No. 3,550,988 issued to Schenck et al. on Dec. 27, 1970. In addition, German Auslegeschrift DAS 1300746 of Aug. 7, 1969 to National Research Development Corp. of London, England, is of relevance.
The various components of reciprocating piston mechanisms such as internal combustion engines, compressors, pumps, or the like, must be designed to endure the detrimental effects of high temperatures and extreme stress loads. Much attention has been focused on pistons in particular and they have been improved in a variety of ways. Many of the improvements are focused upon the elimination of or minimization of the effects of scuffing, i.e., metal to metal contact between the piston skirt and the cylinder wall. For example, the above identified U.S. patents concern themselves with the use of polytetrafluoroethylene (PTFE) for this purpose.
In other cases, such as that exemplified by the construction in the above identified German publication, attempts have been made to maintain a constant body of oil interposed between the skirt of the piston and the cylinder side wall to dampen side to side movement of the piston within the cylinder which can result in such detrimental scuffing.
Moreover, in many cases, complex machining methods are employed in the fabrication of pistons. For example, piston skirts are frequently made somewhat elliptical in shape or provided with a "cloverleaf" shape and contoured to allow for differential expansion due to the varying temperatures along the length of the skirt.